I am trying to do something very similar to the original posted thread but the variables are not strings within the same field. I have a table with 2 rows and 1 column (plus a header) and I need to utilize the value in each row in a raster calculator.
The only way you can extract both values for use in a raster calculator expression I can think of is to run two Calculate Value tools that open a cursor and extract a value, using a cursor construct (or just reading the text file with open()) inside python functions:
file variable -> precondition -> Calculate Value (1) -> Value 1
\
precondition -> Calculate Value (2) -> Value 2
Then use the variables %Value 1% and %Value 2% in the Raster Calculator. You need two Calculate Value tools because that tool can only return a single value.Example Calculate Value expression:f(r"%input file%")
Example code block:def f(file):
fil = open(file)
recs = fil.readlines()
# extract first item on second line of text file
# (remove newline, convert to list, get first item)
return recs[1].strip().split()[0]
From a file like this:
field
1
2
the above function will return "1". WARNING - if you return zero, this is evaluated as False and the processing chain will halt. So I hope you don't need zero. You can work around this by transforming the value (say, add one) and transforming it back (subtracting one) in your map algebra expression.
